ALPHA BRASS

[M-61]

Anyone have experience with http://alphamunitions.com/

In particular their SRP 308.

If so what is the diameter of the flash hole?

 

[Rick300]

Their SRP .308 is .080".
This is a response from them when I asked them about that:

Rick,

First off thank you for purchasing our 308 SRP brass, and for the question concerning our small primer pocket large flash hole setup. There has been a lot of debate back and forth concerning small vs large flash holes, and most of it is just that, debate. It is hard to find any kind of confirmed study. This answer may get a little long, but its a question deserving of such an answer.

First, we have only performed testing on larger volume 308 cases, being the 6.5 creedmoor, 260 rem. and 308 win. There is a lot of history from benchrest shooters who have looked at flash hole size within the PPC family. The results of each case (ppc vs 308) individually cannot be assumed true for the other size cases. Due to gas pressure being highly sensitive to volume (PV=znRT, ideal gas law), and many other factors, it is not valid to assume the results for one particular case must transfer to another case. That said, I'll discuss more what we have seen and found.

Lets hit some background first. People speak of the "jet affect" which was assumed in Percussion Primers, Design Requirements by E.R. Lake, 1970 where he states "as the size of the flash hole is decreased, then the pressure of the [primer] products and the length of their "spit" is increased". Simply put, the smaller the flash hole the greater the length of the jet the primer creates. Going through this report there is zero data backing up the jet affect for our specific application (rifle ammo). A further study, most popular and known in the shoooting industry was performed by German Salazar, 2011 Large vs. Small Flash Hole Test, which presents photographic results which may contradict the "jet affect". Salazar shows images of a large flash hole primer pocket appearing to visually produce more "spit" or "flash" in comparison to the small flash hole. Again, this is all visual results with no quantitative test data.

The reason I wanted to hit on the past research or common knowledge in the shooting industry is that people believe this stuff and speak like it is the 100% undeniable truth, when there is no true data to back it up. We started looking into the large vs small flash holes and have shown the affects of the flash hole on the end result, being the consistency of velocity. Our tests have taken identical cases, except for the flash hole size, and observed the performance characteristics of both. There is a lot of detail I could go into for the setup, but I'll save that for the technical article. We first found a velocity node to shoot well then loaded the same load into the test cases. These were then shot out of the same gun, and recorded using the same chrono (lab radar setup).

In standard conditions we found to have slightly better results (velcoity ES and SD) with the small primer pocket large flash hole setup, now is it a huge difference that would blow everyone away, no. However, testing at extreme low temp conditions we did show the velocity ES difference between the large and small flash holes opens wider.

It is my opinion that there is a balance of both primer and flash hole size to produce the best velocity ES. I think for optimal results you want to use the smallest primer possible which effectively ignites the powder charge. There is too much variance in primer ignition pressures that, I think, leads to much of the pressure variance in firing, consequently affecting the bullet velocities. It is possible (my THEORY.. just a theory...) that the jet affect could actually worsen the inconsistencies of the primer ignition creating greater inconsistencies in the powder ignition.

Anyway, really appreciate the question and I hope this helps!

Thanks,

Andrew Rixon

 

[M-61]

An answer in 24 hours from Alpha:


The diameter of our SRP flash holes is .080. Please let me know if you have any other questions.

 

[Dusty Stevens]

I think that was a very good answer. Sounds like a good company that has answers.

 

[Mr buttersworth]

I have 200 srp 308 win from alpha, the tolorences of the 200 pieces are better than 100 lapua Palma brass. For 200 it had a weight variance spread of .9 grains and length variance spread of .004.
Lapua for 100 cases weight variance spread was 1.2 grains and length was .004
only kinda down side to the alpha is the primer pockets are really really tight, I started only putting 10 primers in my hand primer for the first 3 firings lol.
After that they were normal tight, I'm on the 5th firing of a load of 44.2 of varget w/185 juggs and will not go back to lapua.
buy some, you will not be disappointed I promie

 

[wboggs]

I have found the neck tension to be very consistent. As others have mentioned, quality control is excellent. I ran some tests on LP and SP with a very accurate 260 load. using h4350. Velocity was down 40-50 fps and standard deviation was cut in half.

 

[tbeasley]

You will not be disappointed in Alpha Munitions Brass. They build and prototpe brass till it' RIGHT. Something that has been lacking in the industry these days. They listen to the testers of their brass and fine tune before releasing.
13 firings on same 6 pieces and ES under 10 and SD's range 3.5-5. Never cleaned or re-annealed the brass. Took it straight from gun to reloading table and back to gun. It's really good stuff...